/Engine/Source/Runtime/Engine/Classes/Kismet/KismetMathLibrary.h
Utility for mirroring this transform across a certain plane, and flipping one of the axis as well. (Assumes Matrix represents a transform)
static FMatrix Matrix_Mirror ( const FMatrix & M, [TEnumAsByte](API\Runtime\Core\Containers\TEnumAsByte)< [EAxis::Type](API\Runtime\Core\Math\EAxis__Type) > MirrorAxis, [TEnumAsByte](API\Runtime\Core\Containers\TEnumAsByte)< [EAxis::Type](API\Runtime\Core\Math\EAxis__Type) > FlipAxis )